Visual pigment analogues formed from precursor aldehydes and cattle opsin will be studied by kinetic and spectroscopic (UV and CD) methods. Intermediates in the photochemical bleaching of visual pigment analogues formed from 5, 9 and 13-desmethyl retinal aldehydes and opsin will be isolated at low temperature and their spectroscopic (UV and CD) properties measured. Synthesis of B-apo-carotenals will be begun in order to determine the effect of chain length on chromophore-protein interaction in visual pigments.